We are studying the molecular biology of TGF-alpha and TGF-beta for the relationship between structure and function. The chemically synthesized genes (normal and altered genes) will be expressed in bacteria of cultured cells to study the activity in vitro as well as in vivo. In vitro assays include measurement of soft-agar colony forming activity and receptor binding. The altered genes in retrovirus vectors will be inserted into rat embryos to study the function of these growth factors during normal development.